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SOTA

On Sunday the 27th of October, I activated Mt Gawler, VK5/SE-013 for the Summits on the Air Program.

I thought I’d kill 2 birds with one stone, as this date was also the day of our 1 year anniversary lunch for SOTA in VK5, to be held in at the Kingsford Hotel in the town of Gawler, just a short distance from the mornings activation. I thought I’d go down early, and knock over the summit before enjoying a nice meal and catch-up with the great bunch of VK5’s that participate in the SOTA program.

Not surprisingly, just as I got going 1st thing on the Sturt Highway coming down, I found myself driving behind a familiar vehicle…Larry, VK5LY was travelling in front in his distinctive Toyota Hilux, bristling with antennas! I had gathered Larry was on the way down for the VK5 get together, so I gave him a shout on the local repeater, and sure enough, he was heading down early to activate Mt Gawler as well!

Great minds think alike, and I was pleased that this was going to be a dual activation. Larry is great fun, and a very knowledgable fella as well…we chatted most of the way down to Truro and beyond on 2M simplex to pass the time which made the trip less boring. Before we knew it, we had stopped for fuel, a quick bite to eat and were now scouting out Mt Gawler…

Mt Gawler is just north of Adelaide, and is worth 2 points. It’s an easy access Summit and can be activated from public roadside land at a couple of places that are well within the activation zone.

We found a location where there was a small clearing not very far from the actual Summit itself to operate from, parked the cars and walked to set up the gear.

We decided to just use the one squid pole and share the activating with just the one antenna/rig combination…Larry mentiond that he had a new “experimental” antenna he was willing to try but doubted, and was also keen to give his newly acquired X1M qrp Rig another workout.

Larry’s X1M QRP rig…

We strung up the Larry’s doubtful endfed contraption with its mystery matchbox, plugged it in to the X1M and instantly found that we weren’t hearing much…at all…not even band noise…after self spotting on SOTA watch, we put out a few calls but it became obvious that our signal was waaaaay down, as local VK5’s were barely copying and our best report was 3 x 1!!! The decision was made to change the antenna to a link Dipole, which Larry pulled out from his trusty antenna box. We quickly pulled down the original antenna and hoisted the replacement up in record time as we were keen to work some stations before and after UTC changeover…this was a vast improvement , and we began to make contacts, but signals were still down a bit. We then switched rigs to my FT817ND an i noticed an immediate increase in the background noise, whether this was because of increased sensitivity or just having louder audio, it was a lot easier for me to work stations, which had now had started to form a nice little pile up for both Larry and myself.

Larry, VK5LY working the pileup on 40M…

Daytime conditions on 40M were not that flash, something I have noticed on 40M since the spring equinox at the beginning of this month. We switched to 30M briefly before packing up to head of for lunch, and self spotted on SOTA watch. Ed, VK2JI/P on VK2/HU-076 popped up with a very nice signal for a S2S…followed closely by Tony, VK3CAT with an equally strong signal. I feel 30M is the way to go heading in to summer for these morning activations, signals just seem that much better than 40 lately. Hopefully more activators and chasers will use this band.

VK5LA operating 30M…(VK5LY Photo)

All in all a successful activation, even though conditions weren’t all that great. I was a bit disappointed in the X1M QRP rig, It doesn’t have enough volume in its recovered audio for me to be even remotely interested in purchasing one. As a wearer of hearing aids, I need my audio to be LOUD! The display, although bright enough in daylight to read, was too small for my liking. It also seemed a little “deaf” on RX, like me!!! Larry mentioned that there was no AGC action in the radio either. They are considerably cheaper than an FT817 though, and would be a consideration for those looking for a SOTA capable rig on a budget…

Larry and I packed up afterwards and headed into Gawler for the 1 year VK5 SOTA anniversary lunch at the Kingsford Hotel. This was extremely enjoyable, and I was able to catch up with some of our other VK5 SOTA tragics, including Paul VK5PAS, Ian VK5CZ, John VK5BJE, Keith VK5OQ, and Andy VK5AKH and others, where we all enjoyed a few beers/wines and some fabulous food. Various bits and pieces of radio gear were pulled out of a variety of bags for show and tell, which capped off the afternoon nicely!

Here is my take on the Linked Dipole antenna which has proven popular for SOTA work…

For some upcoming activations, I needed to put together a linked 20-30-40 M dipole as an alternative antenna to the EFHW I had built for my first activation on Mt Lofty.

While thes antennas work well, I felt that those using a linked dipole were putting out a slightly better signal, hence my interest…

Thes linked dipole antennas are available to buy if that’s your thing but I much prefer to make my own…I have been hoarding stuff in my “Junk Box” for years so I had just about everything I needed, except the centre support. For this, I decided to cut one out of some scrap plastic I had kept. This plastic is thin, about 2mm thick but quite stiff, although it has a nice flex if put under stress. I came from a promotional “point of sale” tray that fitted under a printer from my work place. I have dozens of the bloody things! It proved easy to cut with a good pair of sharp scissors, and was easily shaped with my leatherman tool knife blade. Conveniently, it had a nice lip bent over past 90 degrees, perfect for mounting the BNC connector…

Although perhaps not really necessary at QRP levels, I decided to fit a choke balun at the feed point to keep any rf from flowing on the outside of the coax. I used a Jaycar CAT. No. L-1238 Toroid as I had some on hand, and wound about 8 turns of some excess RG-316 and soldered one end to the BNC connector while the other ends of the coax were crimped to each dipole wire…

Centre insulator on the Squid pole ready to raise up

For the dipole links I used automotive spade lugs, as I had some on hand…other ideas would be power pole type connectors or even bullet style connectors, whatever you think is a fair thing! I crimp mine, and use Aluminox paste in the joint to provide longevity. The insulators are actually from the packaging holding my youngest lads last Nerf Gun firmly to the cardboard! I live by the motto, “never throw anything out!” – here it came in handy…

Dipole Link, I used automotive spade lugs and the insulators are left over bits of plastic from Xmas toy packaging!

I have mounted a bit of PVC pipe in the front yard so that I can slip my 9M Squid pole over it and quickly raise it for operating or testing out a new antenna. I used this to gear effect today, and starting on 20m, I was able to trim the dipole lengths and add the next sections in a relatively short time. I was also very fussy with the tuning, and trimmed each band to 1:1.2 or better. This lets the FT-817 develop full power into the antenna on each band – important when operating at 5watts QRP, every milliwatt counts!

Testing the link Dipole

I got to try out the linked Dipole during my latest Sota activation, and it seemed to worked well on the 3 bands it was designed for. Due to the very strong winds I was only able to get around 70 degrees of angle between each leg, where as I like 100 degrees or better as I believe there is some cancellation of the TX signal below this angle…

Squid pole bending in the wind…

Success!

So there you have it, much more satifying than buying a ready made unit, cheaper as well, I think I’ll probably end up keeping the EFHW in the kit as its only one piece of wire, and I bet that it would be relatively straight forward to make a linked version of one of those as well.

Thats the beauty of this hobbly, you can experiment at will and build stuff to your heart’s content, or if your time poor then there are usually plenty of companies the affer what you want and are very willing to take your money!

After a couple of months of not chasing much SOTA with life getting in the way, I was able to fire up the HF rig from around 8:30 am on Sunday morning and have a good listen around. I was able to pretty much keep the rig on all day and listen out for the goat bleating alert from the most excellent SOTAgoat app to let me know of what was happening around VK!

This is what I ended up with for the day, between chores, shopping, and some plumbing repairs and the construction of an End Fed Half Wave for 40M

The End Fed Half Wave antenna (EFHW)for SOTA portable operation…from bits and pieces in the Junkbox…

Whilst leisurely chasing activators this morning, I also took the opportunity to rummage through my Junkbox to see if I had all the bits and pieces to make an end fed half wave antenna for the 40M band. My main antenna for 40m at the home station is a Butternut HF2V, and is a good performer for SOTA chasing work, but I intend to activate a few summits in the near future, and although I’m well equipped for VHF, I need a good portable antenna for my planned activations.

I did a bit of research on the EFHW during the previous week, looking at what was written on the Internet about the antenna and what kits, if any, were available and at what cost. I found a few, but decided that the best way forward was to knock one up with the stuff I had on hand…

There’s not much to them, and the whole thing took me about 2 hours to assemble.

The VK5LA EFHW Tuner

Firstly, The circuit – There seemed to be a fair variation on the theme in terms of components used but ultimately, it’s just a tuned circuit set to resonate at the frequency of interest. Matching – some used link coupling of the tuned circuit, some with a tap up a few turns from the earthy end of the inductor. I went with this…

Hand drawn Circuit

Quite a few of the circuits used the Yellow toroid but I didn’t have one so I used a T50(Red) one that I had on hand. 24 Turns was about average for the schematics I gleaned and the tap 3 turns in from the earthy end seemed to be standard. The capacitor was one I had on hand that came from the board of a 70’s am transistor radio that was long ago junked.

Wiring diagram

I had a small black plastic Jiffy box on hand so I mounted everything in it and soldered it up as per the above diagram. The red banana plug socket on the side was added just in case if I need it for later. The black banana plug socket is for a counterpoise wire if desired. I found that I didn’t need one when testing, I think because I’m using a tap on the inductor L1. Dead simple!

A peek inside…

I then cut a 21.6 m length of light weight hook-up wire for the 40M band and attached a banana plug to one end and a lug to the other. I attached the lug end to the tip of my 9 meter high Squid Pole that I had set up in the front yard, and the other end to the Tuner and FT817 via a short BNC to PL259 lead set up on a table.

Table top portable…in the front yard!

To be perfectly honest, I wasn’t really expecting it to work, I plugged it in and turned the FT817 to the 40m band and selected LSB…the dial was down at the bottom of the band and to my surprise I heard a few stations as I tuned up to around 7.1 MHz. Well, “here goes nothing” I thought as I began to turn the variable cap on the tuner, all of a sudden the noise sharply increased and a smile emerged on my face! I knew then it was working and a brief “VK5LA testing” on a clear frequency allowed me to adjust the SWR to nothing on the Rig with the Variable capacitor at around 1/2 mesh…pretty well where it should be…

The complete EFHW 40M antenna packs down to a small package…

Now the acid test! did it work? could it make contact? It seems that it was certainly hearing ok, with a lively 40m band jumping out at me…I was about to find out as heard the bleat of my SOTAgoat alert on my iPad, letting me know that Alan, VK3HRA/P on VK3/VC-002 Mt Donna Buang was calling CQ on 7.103 MHz. I tuned to his frequency, and he was a good signal, very readable at 56…To my delight, Alan came back with a 58 for me for my first EFHW contact.

I’m certainly impressed by the EFHW antenna, and I’m looking forward to giving it a run out on a summit in the very near future…in the mean time, I’ll try different configurations like an inverted L and V, and perhaps as a vertical, to see how it goes. I might even adapt it by making the wire “linkable” for 10/15/20/40 like the Link Dipole that others swear by.